1. Field of the Invention
This invention relates to a structure of a sheathed wire, in which the sheathed wire, having a conductor covered with a sheath, is gripped by a resin-molded water-stop member, and a water-stop treatment is applied to the sheathed wire by ultrasonically welding the water-stop member.
2. Related Art
In one known conventional water-stop structure of a sheathed wire as shown in FIGS. 9 and 10, a sheathed wire 60 is held between a pair of upper and lower (FIG. 9) resin-molded water-stop members 61, and ultrasonic waves are applied from an ultrasonic horn 62, disposed above (FIG. 9) the water-stop members 61, to the water-stop members 61 to weld the water-stop members 61 to conductors of the sheathed wire, thus achieving a water-stop treatment (see JP-A-7-320842 and JP-A-11-250952).
There is also disclosed an ultrasonic welding horn which is so constructed as to prevent forced-out conductors of a wire from being cut at the time of welding the conductors of the wire to a metal plate. In this ultrasonic welding horn, continuous recesses and ridges are formed in a side wall of the horn, and the recesses serve as relief spaces for receiving the force-out conductors (see JP-A-2000-202642). This ultrasonic welding horn is designed to weld the wire to the metal plate and also to prevent the wire from being cut by the ultrasonic welding horn, and this ultrasonic welding horn is not designed to apply a water-stop treatment to the sheathed wire.
Further, there is shown a method of welding or fusing a first synthetic resin member and a second synthetic resin member together (see JP-A-2000-326413). A recessed portion against which an ultrasonic horn is adapted to be pressed is formed in the first synthetic resin member, and the horn is pressed against this recessed portion, and therefore even when a bottom surface of the recessed portion melts, this molten resin will not flow out to the surface of the first synthetic resin member (see JP-A-2000-326413). This method is a method for welding the two synthetic resin members together, and does not relate to a structure of applying a water-stop treatment to a sheathed wire.
In the above conventional water-stop structure of the sheathed wire 60 disclosed in JP-A-7-320842 and JP-A-11-250952, the distance L of transmitting of ultrasonic vibrations from the ultrasonic horn 62 increases with the increase of the thickness of the sheathed wire 60 to be subjected to the water-atop treatment, and therefore the ultrasonic waves are not efficiently transmitted, which results in a problem that much time is required for this processing, so that the cost inevitably increases (see FIG. 10). And besides, the larger the thickness of the wire is, the less the ultrasonic vibrations are transmitted to the whole of the wire to be welded, and as a result the melting and filling of the resin are not sufficiently effected, so that the water-stop performance is lowered.